Road traffic monitoring is an important topic in road traffic management and navigation system. The traffic monitoring may be used to generate basic information for the road traffic, such as average speed of a vehicle, travel time of a road, road congestion degree, and incident position etc. By providing real-time basic information, the navigation system can learn the road traffic situation in time and reasonably arrange driving trajectories for the vehicles, thereby effectively reducing the congestion and avoiding collisions.
Common solutions for monitoring road traffic based on traffic sensors (such as inductive loop detectors) and GPS floating cars (such as taxis provided with GPS) have been applied to the urban roads. However, this solution has not been applied to the vast suburban roads and inter-cities roads. This is mainly because that: 1) the traffic sensor is expensive in both deployment and maintenance, and it is not suitable for suburban deployment; 2) the GPS floating car based solution highly depends on the number of floating cars on the monitored road, and in fact there is few floating cars running on the suburban and inter-cities roads.
Currently, mobile communication networks, such as 2G/3G mobile communication networks, have covered over 90% of the regions of many counties and over 70% people use cell phones everyday. When communication behaviours happen, such as send/receive a short message, initiate/receive a call or perform handover during a session, the network would record the position of the base stations currently providing the corresponding service. Thus, the mobile communication networks may also be considered for monitoring the road traffic.
In the existing mobile communication networks based road traffic monitoring solution, a moving speed of a mobile user may be calculated by recording the position information and time of two continuous communication events when the mobile user takes two communication behaviours on the monitored road, and therefore the traffic situation of the monitored road may be evaluated. However, such a solution depends on the number of the communication events happened on the monitored road, and it can not work if no communication events happen on the monitored road.
In addition, this solution is disadvantageous when the time difference between two continuous communication events is large, because the speed of the vehicle usually varies seriously during a long time interval. Typically, the suburban roads and inter-cities roads have different traffic environment, for example, for an inter-cities road travel some villages, the travel speed of the vehicle varies with positions, for example, it would be slow when approaching a village and would be fast when leaving the village. Thus the solution can not evaluate the traffic situation of a road accurately.
Most mobile communication networks have a function of active positioning, which has been widely employed in Location-Based-Service (LBS). By actively paging the phone of the mobile user, the position of the mobile user can be determined However, the function of active positioning will trigger signalling interaction between the base station and the mobile phone, which would cost a large amount of wireless resources.
U.S. Pat. No. 6,198,630 a system for tracking the location of, and for providing cellular telephone handoff for, a mobile cellphone user as the cellphone user moves from one cellzone to another. However, there is still a need in the art to provide a solution to alleviate the above mentioned problems.